Global Positioning System - About GPS
|Figure 1: A GPS
The Global Positioning System (GPS) is a network
of satellites that orbit the earth. "At any given time, there
are 24 active satellites in the constellation. The constellation
is composed of six orbital planes, each containing four satellites."
2000)[See Figure 1]. GPS receivers can compute positions on
the Earth using time and ephemeris (i.e. orbital position) information
provided by the satellites.
GPS is ideal for demining, but it has many other applications.
GPS revolutionized navigation and tracking. Whether it be by land,
water, or air, GPS can be used to get just about anything from point
A to point B. Various companies are using GPS to keep employees
and products on track by mounting antennae on company vehicles.
GPS is also used in missle guidance and for imagery correction through
use of ground control points. Essentially, GPS applications possibilities
are endless. GPS gives the users the ability
to create, via these positions, their own custom data. The data
can later be used in a GIS to generate spatial data layers.
Three GPS Segments
The network of satellites orbiting the Earth. These satellites have
very accurate atomic clocks and broadcast radio signals to the Earth.
User segment: The users and their receivers.
The receivers have less accurate clocks and use the signals sent
by the satellite to calculate position.
Control segment: "Consists
of five monitor stations (Hawaii, Kwajalein, Ascension Island, Diego
Garcia, Colorado Springs), three ground antennas, (Ascension Island,
Diego Garcia, Kwajalein), and a master control station (MCS) located
at Schriever Air Force Base in Colorado that monitor the satellites."
There are three steps for utilizing GPS in mapping.
Before the data is ever collected, planning
must occur. After developing a data collection strategy, field data
is then obtained. Finally,
the data is processed
and put into a useful form.
Mine Clearing Standards and Survey Types may be helpful in realizing
the data collection needs.